The easiest way to handle your average planar boundary (including teleportation circles) is to assume that nothing (energy, matter, anything) will go through it without a direct action from a creature. ie - only items that a creature is carrying, dragging or pushing will pass through.
IOW - cast gate and aim it at the plane of water, and you don't flood the city, however pushing a bucket through and then bringing it back again will result in a bucket full of water.
It just makes spells that do these things easier to handle: they still work for their intended purpose, but unusual tricks like the above are disallowed.
One of the effects of this is that sound won't travel through the boundary - it's a thing, and it's not being carried, dragged or pushed by a character.